Since straight hair is dominant it would be a capital S and curly would be a lower case s. If a straight hair gene was in the genotype it would block out the curly hair, so the only way to have curly hair would be ss.
In order for the recessive curly-haired gene (s) to be expressed in the phenotype, there needs to be no dominant straight haired gene (S) in the genotype.
Much like human skin, a plant has a tissue system which consists of a group of cells that work together for a very specific function and forms the first line of defense against physical damage and disease
This tissue system is called the dermal tissue system, and it is the plant's outer protective coating
The dermal system itself consists of a layer of tightly packed cells called the epidermis
Epidermis regulates exchange of gases and and acts as a protective barrier against any injury or infection
The epidermis in turn is covered with a waxy coating called the cuticle, which helps prevent water loss through the epidermis